Present day digital computer systems typically include hundreds of integrated and discrete components mounted on printed circuit boards (PCBs), the components located on a single printed circuit board being interconnected by wiring or circuits within the printed circuit board. Many computer systems, including most personal computers, include a primary printed circuit board, known as a motherboard, having many of the computer's major components, such as a processor, drive controllers, video controllers, primary memory, interrupt controllers, BIOS and other components, mounted thereon. These printed circuit boards may also include sockets and connectors for receiving additional components, signal cables, component modules, multi-chip modules and for connection to other printed circuit boards.
Additional optional or required printed circuit boards, often referred to as "daughter" boards typically include electrical contacts along one edge which are press fitted into edge connectors secured to the surface of the motherboard. Alternatively, the printed circuit boards, including the motherboard, may all be connected through edge connectors secured to a common backplane.
Although the printed circuit boards are press fitted into the edge connectors, additional support may be required to secure the boards to prevent the boards from disengaging from their edge connectors as a result of vibration or movement of the system cabinetry. Even a slight, possibly unnoticeable, separation between a board and its corresponding edge connector may cause interruptions in the electrical signal paths between the board and connector. The orientation of the edge connectors and installed printed circuit boards, e.g. vertical, horizontal, or some other orientation, may increase the likelihood of a board separating from its connector. Large boards may further increase the likelihood of a board separating from its connector.
To address the above-described concerns, several styles of circuit card retainers have been devised. One such circuit card retainer is disclosed in U.S. Pat. No. 4,198,024, issued Apr. 15, 1993, to Peter J. Cavanna. The disclosed retainer comprises a unitary retention arm which is rigidly attached proximate a card edge connector. The other end of the retention arm is formed into a L-shaped latch which can be pressed into engagement with a printed circuit card installed into the card edge connector. The retainer arm may also be formed in two sections which permits the length of the arm to be varied for accommodation of boards of varying sizes. However, as shown, the installation and adjustment of the retainer arm is relatively difficult. Furthermore, the flexibility of the retainer arm to accommodate boards of varying sizes or which including components or connectors which interfere with the retainer arm, is limited. Connectors or components on the surface or top edge of the card installed into the connector may prevent the utilization of the retainer.